Help--Taillamp Won't Light

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
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ClutchFork
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Help--Taillamp Won't Light

Post by ClutchFork » Sat Apr 13, 2019 12:21 pm

So my right tail light on the 2001 S10 won't light. The bulb is fine. The brake light in same bulb (3157) works fine. I tested and the left, which lights, has 11 volts, but the right side which won't light, has 9 volts (switched bulbs to be sure I had a working bulb). Thinking how my household LED bulbs are bright during a brownout, I grabbed some LED taillights at the store but they won't light in the 9 volt socked, and not even in the 11 volt socket. Now what to do? I can't drive at night, and really should not drive in the rain either. I hope this is not a replace-all-the-wiring-in-the-S10 project, because if it is, it means I start shopping for a new truck or rig up a separate tail light somehow.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Help--Taillamp Won't Light

Post by Rope-Pusher » Sat Apr 13, 2019 4:05 pm

ClutchFork wrote:
Sat Apr 13, 2019 12:21 pm
So my right tail light on the 2001 S10 won't light. The bulb is fine. The brake light in same bulb (3157) works fine. I tested and the left, which lights, has 11 volts, but the right side which won't light, has 9 volts (switched bulbs to be sure I had a working bulb). Thinking how my household LED bulbs are bright during a brownout, I grabbed some LED taillights at the store but they won't light in the 9 volt socked, and not even in the 11 volt socket. Now what to do? I can't drive at night, and really should not drive in the rain either. I hope this is not a replace-all-the-wiring-in-the-S10 project, because if it is, it means I start shopping for a new truck or rig up a separate tail light somehow.
When you measured the voltage, how did you measure it? In the bulb housing are two Positive terminals, one for brake/turn signal and one for the tail/running /parking light. The tail/running/parking light side of the bulb is the dimmer side and the brake/turn signal side is the bright side. It's the design of the bulb that makes one brighter than the other, not the power that is supplied.

If the brake light is fine then your ground connection is probably OK. Then I would suspect that the power wire has a bad connection somewhere.

I don't know how your particular wiring circuit runs, but often there is a wiring loom that crosses over from one side of the vehicle to the other. Since the tail/running/parking lamp on each side should light up the same, whenever the headlice are turned on, then I'd think that your power runs from the 11 volt side over to the 9 volt side and the 2 volt drop is due to a bad connection between them...most likely due to corrosion. you can try to trace that wire between the two lights and clean any connection(s) you can get to, or just run a new wire between them and bypass the corroded connection(s).
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

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ClutchFork
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Re: Help--Taillamp Won't Light

Post by ClutchFork » Sat Apr 13, 2019 9:02 pm

I tested in the socket with the running lights on using a multimeter. The bulbs have dual filaments and contacts on both sides of the base. The one side of course was no power because the brake pedal was not depressed.

Your idea makes sense and should be fairly easy to trace wires across the bottom. In fact, there is some trailer wiring pushed up in there somewhere that maybe the problem. I'll have to investigate that too.

Curious why the LED would not work with it's theoretical lower voltage requirements.

So I looked under there. We have one line coming from the front on the left framerail. There is a connector from it to the rear wiring. Right after the connector is the trailer wiring, which I removed (though maybe should have tested first as could rig a red bulb taped to the bumper for the time being). It was connected to 3 of the 5 wires coming from the connector. Not going to haul any trailers.

So the back part is a bundle from one taillight to the other and spurs to the license lamps. The odd thing is there are three other short spurs leading to little boxes that are about 1/4 to 1/2 inch thick. One on the left, one in the middle, one on the right. The ones on the left and right are identical. The one in the middle is larger. They seem to have no purpose though. At any rate. I still have to trace things out. A logical place to start is where the middle connector comes in but it is going to be a challenge as 18-year-old electrical tape does not freely peel off.

Hey, just found out that a 5-quart oil jug makes a great headrest under the truck. Keep you from getting a sore neck.
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Help--Taillamp Won't Light

Post by ClutchFork » Mon Apr 15, 2019 12:00 pm

All fixed. Stopped by the shop this morning and they fixed in in an hour. $50. They put a jumper wire for the bad taillight and re-did a connector that was corroded, so likely now will have full battery voltage at both taillights. They looked up the wiring diagram and said there are four hot wires (I see five coming from connector, one ground no doubt), one for left brake/turn, one for left tail, one for right brake/turn and one for right tail. He said the left and right sides are on different fuses too.
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theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Help--Taillamp Won't Light

Post by Rope-Pusher » Mon Apr 15, 2019 8:32 pm

ClutchFork wrote:
Mon Apr 15, 2019 12:00 pm
All fixed. Stopped by the shop this morning and they fixed in in an hour. $50. They put a jumper wire for the bad taillight and re-did a connector that was corroded, so likely now will have full battery voltage at both taillights. They looked up the wiring diagram and said there are four hot wires (I see five coming from connector, one ground no doubt), one for left brake/turn, one for left tail, one for right brake/turn and one for right tail. He said the left and right sides are on different fuses too.
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'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

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ClutchFork
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Re: Help--Taillamp Won't Light

Post by ClutchFork » Mon Apr 15, 2019 11:14 pm

No way! Autonomous refuse truck? That is really scary. Why is that guy in yellow suit running away from it. Truck must be backing up to load him as refuse?
Stick shiftin since '77
theholycow wrote:Why in the world would you even want to be as smooth as an automatic? Might as well just drive an automatic...

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Re: Help--Taillamp Won't Light

Post by Rope-Pusher » Tue Apr 16, 2019 12:30 pm

ClutchFork wrote:
Mon Apr 15, 2019 11:14 pm
No way! Autonomous refuse truck? That is really scary. Why is that guy in yellow suit running away from it. Truck must be backing up to load him as refuse?
Must be one of dem "Refuseniks" we us'ta hear about.
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"

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